This invention relates to hydroponics and more particularly relates to a novel and improved method and system for growing plants within a limited space under controlled feeding, irrigation and lighting conditions comparable to those found on a commercial scale.
Hydroponic gardening relates to the growth of plant cultures in inert soils where the necessary nutrients and water are supplied from storage tanks and recirculated as needed for proper feeding. Generally, in the past, successful hydroponic gardening systems have been largely confined to operations carried out on a commercial scale because of the close control required over feeding, temperature and lighting cycles. Another difficulty in attempting to carry out hydroponic gardening on a smaller scale, particularly for the hobbyist, has been the requirement for a relatively large water supply with closely controlled pumping and circulation over predetermined time intervals. For instance, while water must be made freely available to the root system it must be closely controlled in such a way that the root system is not unduly stressed either by the presence of too much water which will cut off the oxygen and kill the root system or by permitting the growth media to dry out over extended time periods. In practice however it is extremely difficult to supply a constant ratio and concentration of essential nutrient elements without expensive analytical equipment and control since these vary a great deal with the type of plant as well as the light, water, temperature and other factors. Accordingly, successful gardening requires not only close control over the circulation of water and nutrient solutions to the growth media but also predetermined intensity and distribution of the lighting for predetermined time periods over the growing surface.
The smaller portable hydroponic garden units now commercially available are largely confined to sub-irrigation systems in which the solution is merely circulated into the growth media and permitted to completely fill the tray containing the growth media followed by draining of the solution usually through the same line employed for supplying or pumping the solution into the growth media. For example, a representative system of this type is disclosed in U.S. Pat. to Robins No. 3,323,253. Other systems employ separate delivery and drain lines but typically are so constructed and arranged as to require that the plant tray be flooded to capacity then allowed to drain. Still other more elaborate systems designed for commercial use employ a filter and pump on the return side for returning the solution from the plant tray to a reservoir or tank. Sub-irrigation systems per se suffer not only from the requirement for large amounts of water but also from the lack of proper aeration of the growth media. If the growth media is irrigated simply by filling the plant tray at period time intervals, then as the water slowly drains out of the tray after filling, the density in packing of the growth media is such that it becomes very difficult for the oxygen to fill or re-enter the pockets or voids created by removal of the water beneath the upper surface of the growth media.
Top irrigation systems have also been employed primarily on a large commercial scale for irrigation of natural soil in which the plants are watered usually by a spray or mist solution above the surface of the growth media. Typically in top irrigating systems the nutrient solution is not recirculated and the water and chemicals are wasted. However, its advantage resides in that it affords better natural aeration of the growth media, there is not as much danger of spreading disease and the costly recirculation systems are avoided. Again extremely close control is required during each watering cycle to insure that the soil is not unduly saturated; and to the best of my knowledge a top irrigation system has not been devised which can be used interchangeably with a sub-irrigating system in a self contained, portable gardening system for the home.
Lighting systems presently available for hydroponic gardening have been vastly improved over the years so as to provide high intensity lighting at the proper wattage to simulate outdoor growth of various plants under natural light. However, systems commercially available for lighting have been extremely expensive and in most it has been very difficult to assure uniform even light distribution with a limited lighting cycle in an inexpensive manner which would make it feasible for use by the hobbyist.